ST. LOUIS - The search is on for the man who attacked a Cherokee Street business owner in broad daylight.

The victim is a 64-year-old Vietnam refugee, suffering from cancer. NewsChannel 5’s Rebecca Sheehan spoke with his sons, devastated by the suffering of a man who gave everything, so they could all enjoy the American Dream.

Tyler Ruby was 4 when his family fled Vietnam for a better life.

“It was in 1979," he said. "I remember the kids were on the adults’ shoulders, wading through water at night.”

His family landed in St. Louis with literally one dollar.

“At the time my sister was one year old and she was crying, so my dad took that dollar and bought her a soda, and that calmed her down," Ruby said. "So we basically started with nothing. He started this business from scratch, and I look up to him because he’s always taught me that hard work pays off.”

Brothers Tyler Ruby and Vu Le tell me they their family became even closer when their 64-year old father was diagnosed with cancer. It’s now Stage 4.

“It really weakened him, so he started doing a lot of walking to regain some of his strength,” Ruby says.

The elder Le thought walking through the alley near his business at noon on a Monday would be safe, but it wasn’t. Surveillance footage shows a black male, about 6-foot-2, wearing a shirt with the letter “R” on it, walking past Mr. Le, then pausing at the end of the alley.

When the victim caught up, the suspect turned, and punched him in the nose. The victim fell hard, hitting his head on the pavement. He had a seizure, and bit his tongue in two.

The brothers were inside the family business when it happened.

“What I saw, it’s traumatized me,” Ruby said.

The victim is now in critical condition, with bleeding in his brain and fractures in his face. Le says his father may never completely heal.

“His body is weakened from the chemo, from the cancer, and there’s a lot of risk of infection," he said. "They want to put in plates and screws, but it’s such a major complication with the cancer, that’s a major operation.”

Police say the suspect got away with the victim’s wallet. This family now hopes someone recognizes this man to bring him to justice.

“Something that took a matter of seconds has now devastated my father lifelong," Le said, "and over what? Money, credit cards?”

If you have any information on the suspect, contact CrimeStoppers at 866-371-TIPS.

A neighboring business owner started a GoFundMe page to help the Le family defray medical costs.